Useful tool for searching for images on the interweb - Google, Bing, Flickr, DuckDuckGo are the engines currently available. Once you find an image, you can long-press it to bring up just two options for downloading it:
(1) Save (to your Photo Roll)
(2) Copy the image.
That's basically it as far as I can tell. And it does it well.
Of course, it could do more, thus 4-stars instead of 5-stars. Some (apparently) missing features that would be nice to see in an update:
1. A third download option to open the image in another app, e.g., your favorite iOS photo editor.
2. Batch download (i.e., multiple selection).
3. Search by image to find visually similar images (e.g., as you can do in a Google Image search at least).
4. Advanced image search filters, like format, file size, license type, etc. (again, as you can do with Google Image search).